Making a textbox only accept numbers and commas

You could implement a custom TextBox by inheriting the original and adding some custom code (or just use the custom KeyPress code on your existing box).

class NumberTextBox : System.Windows.Forms.TextBox
{
    private readonly List<char> valids = new List<char>() { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', ',' };
 
    public NumberTextBox() : base()
    {
        this.KeyPress += new KeyPressEventHandler(NumberTextBox_KeyPress);
    }
 
    void NumberTextBox_KeyPress(object sender, KeyPressEventArgs e)
    {
        if (!valids.Contains(e.KeyChar))
        {
            e.Handled = true;
        }
    }
}

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void NumberTextBox_KeyPress() should be implemented as below. Sorry, I posted incorrect code for that.

void NumberTextBox_KeyPress(object sender, System.Windows.Forms.KeyPressEventArgs e)
{
    if (!valids.Contains(e.KeyChar))
    {
        e.Handled = true;
    }
}

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If you want backspace to be allowed, then change the char list to the following:

private readonly List<char> valids = new List<char>() { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', ',', '\b' };

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have a look at http://www.emoreau.com/Entries/Articles/2003/03/Creating-your-own-Windows-Custom-Control.aspx

I get the error:
'Contains' is not a member of 'System.Array'.      

Okay, Just had to change  valids()  to an arraylist so i could use the contains method. Thanks. It seems to be working just fine.